Effect of hexylresorcinol concentration on chemical, bacterial, sensory variations and shelf life of frozen cultured white leg shrimp (Litopenaeus vannamei)

Processing technology is important for the export amd import of shrimp and should be selected with regard to the needs of the market and be accepted by GRASS. Therefore, this project was carried out to achievie a proper technology, to maintain chemical, bacterial and sensory qualities and also the safety of shrimp in terms of food hygiene, to increase the shelf life and to detect the proper concentration of 4-hexylresorcinol for processing white leg shrimp. This research evaluated the hypothesis of 4-hexylresorcinol being able to preserve frozen cultured white leg shrimp. The treatments included shrimp immersed in 4-hexylresorcinol (at concentrations of 0.15 % and 0.05 % for 10 minutes) and antioxidant-less shrimp. No Pseudomonas, Vibrio parahaemolyticus, Escherichia coli or Hydrogen disulfide-producing bacteria were observed in either experimental or control samples. Unlike the control samples, Coliform bacteria were not observed in the experimental samples. TVB-N, Trimethylamine, Thiobarbituric acid, Free fatty acids, Peroxide value, moisture, total bacterial counts and Staphylococci counts of experimental and control samples showed significant difference during the storage period (P<0.05). unlike total bacterial counts, Staphylococcus bacterial counts, Coliform bacterial counts, free fatty acids, peroxide value, Thiobarbituric acid, TVB-N and Trimethylamine factors, the factors of pH and moisture of the experimental samples showed no significant difference compared to the control samples (P>0.05). The sensory quality and the shelf life of experimental samples showed significant difference compared to control samples (P<0.05). Chemical, bacterial and sensory factors and the shelf life of 4–hexylresorcinol showed no significant difference among different concentrations (P>0.05). based on the Iranian National Standards, the test samples had a good quality during the period of six months in frozen storage ( -18 oC)  but the control samples lost their sensory quality in lower than one month.

Key words: White leg shrimp, Sensory evaluation, Chemical factors, Bacterial variations, 4–Hexylresorcinol.